1. Field of the Invention
Exemplary embodiments of the invention relate to a backlight unit and a display device.
2. Description of the Related Art
In general, a typical large-sized display device includes a liquid crystal display (LCD), a plasma display panel (PDP), and the like. Unlike the self-emission type PDP, the LCD needs a backlight unit because it generally does not have a light emitting device.
A backlight unit used in the LCD may be divided into an edge type backlight unit and a direct type backlight unit depending on where light sources are disposed. In the edge type backlight unit, light sources are disposed at the left and right sides or upper and lower sides of an LCD panel and a light guide plate is used to propagate the light emitted from the light sources, thereby obtaining light uniformity and allowing the panel to become ultra-thin.
The direct type backlight unit is used for a 20 inch or larger display. In the direct type backlight unit, a plurality of light sources are disposed under a panel and have superior light efficiency than the edge type backlight unit. Thus, the direct type backlight unit is commonly used for a large-scale display.
Conventional edge type backlight units or direct type backlight units employ cold cathode fluorescent lamps (CCFLs) as light sources.
However, the backlight unit employing CCFLs is disadvantageous because, since power is constantly applied to the CCFLs, a great deal of power is consumed, a color reproduction range (i.e., gamut) is about 70% of that of a CRT, and the addition of mercury causes an environmental pollution. Thus, in an effort to address the problems, currently, research for a backlight unit employing light emitting diodes (LEDs) as a substitute is actively ongoing.
The use of the LEDs for a backlight unit allows for turning on and off a portion of an LED array and can remarkably reduce power consumption. In the case of an RGB LED, a 100% or more of a color reproduction range of an NTSC (National Television System Committee) can be obtained to provide more vivid picture quality. In addition, the LEDs manufactured through a semiconductor process are less harmful to the environment.
Some LCD products employing the LEDs as a backlight unit having the foregoing advantages have been launched, but because their driving mechanisms are different from that of the existing CCFL light source, the driver, PCB, and the like for such products are expensive and may not be cost effective. Thus, conventionally the LED backlight unit is employed only for high-priced LCD products.